Magnetic losses in composite materials

Summary, in English

We discuss some of the problems involved in homogenization of a composite material built

from ferromagnetic inclusions in a nonmagnetic background material. The small signal

permeability for a ferromagnetic spherical particle is combined with a homogenization

formula to give an effective permeability for the composite material. The composite material

inherits the gyrotropic structure and resonant behaviour of the single particle. The resonance

frequency of the composite material is found to be independent of the volume fraction, unlike

dielectric composite materials. The magnetic losses are described by a magnetic conductivity

which can be made independent of frequency and proportional to the volume fraction by

choosing a certain bias. Finally, some concerns regarding particles of small size, i.e.

nanoparticles, are treated and the possibility of exciting exchange modes are discussed.

These exchange modes may be an interesting way to increase losses in composite materials.

• Author: Jörgen Ramprecht; Daniel Sjöberg
• Department/s: Department of Electrical and Information Technology
• Publishing year: 2008
• Language: English
• Publication/Series: Journal of Physics D: Applied Physics
• Volume: 41
• Issue: 13
• Links: http://dx.doi.org/10.1088/0022-3727/41/13/135005
• Document type: Journal article
• Publisher: IOP Publishing
• Topic: Electrical Engineering, Electronic Engineering, Information Engineering
• Status: Published
• Research group: Electromagnetic theory
• ISBN/ISSN/Other: ISSN: 1361-6463